Old stars gleaned neighbors’ gas, Hubble data show

Snatching matter helps blue stragglers stay hot and look young

FAKING YOUTH Some of the blue stragglers (circled) in the open star cluster NGC 188 have white dwarf companions, confirming that the hot, blue stars once stole material from the now-dead ones to stay young looking.

K. Garmany, F. Haase NOAO/AURA

Stealing keeps some stars looking young. The thieves, called blue stragglers, swipe material from a neighbor, leaving behind a dead stellar companion as a calling card, data from the Hubble Space Telescope show.

Natalie Gosnell, an astronomer at the University of Wisconsin–Madison, and her colleagues discovered three blue stragglers that share orbits with white dwarfs, the remnants of dead stars. The findings, posted January 29 on arXiv.org, match astronomers’ ideas about what would be left if a blue straggler took gas from a now-defunct companion star. The stolen goods allow the blue stragglers to burn hotter and look bluer, as a much younger star would.

“These blue stragglers absolutely did form from taking matter from another star. It is the first time we have been able to say that for a specific population of blue stragglers,” Gosnell says.

Determining how blue stragglers pilfer matter

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